1. Field of the Invention
The present invention relates to piezoelectric ceramic-polymer composite transducer arrays, and particularly to acoustic transducer arrays which are suitable for rugged use.
2. Description of Related Art
One example of a rugged use for an acoustic transducer array is as a hydrophone for use as a sensor or transmitter on the hull of an icebreaker or surface-mounted on other equipment used in arctic waters.
At present, such an array, e.g., that used as a hull-mounted array on a ship fitted as an icebreaker, is mounted beneath a reinforced plastic xe2x80x9carray windowxe2x80x9d approximately four inches thick. The array is separated from the reinforced plastic window by a layer of seawater. Thus, the plastic window serves as a part of the ice-breaking shell of the ship, and the plastic window and the water layer act as a protective lens to shield the array from impact damage from contact with ice at and below the water surface.
The plastic and water layers, however, also tend to decouple the array from the water medium, significantly deadening the sensor sensitivity and its acoustic output.
There is a long-felt need for an acoustic array for use in such extreme applications which combines the advantages of ruggedness, e.g., impact resistance, and high sensitivity, particularly at low frequencies. The invention described hereinafter meets such a need.
Accordingly, it is therefore an object of the present invention to provide an impact-resistant acoustic transducer having a honeycomb structure including a plurality of cells with each cell having a piezoelectric transducer.
It is another object of this invention to provide an impact-resistant acoustic transducer having a honeycomb structure including a plurality of cells, each of the cells having a piezoelectric transducer and each piezoelectric transducer comprises at least one piezocomposite element.
It is a further object of the present invention to provide a piezocomposite transducer array suitable for application in a rugged environment.
It is yet another object of this invention to provide an acoustic transducer array as a hydrophone for use as a sensor or transmitter on the hull of an icebreaker.
It is a further object of this invention to provide an array of piezocomposite transducer elements comprising a plurality of piezoceramic rods encapsulated in a polymeric matrix to form a piezocomposite body.
It is another object of this invention to provide a honeycomb structure having a plurality of cells, each of the cells comprising a 1-3 piezocomposite element.
It is another object of this invention to provide a honeycomb structure having a plurality of cells, each of the cells comprising a 2-2 piezocomposite element.
It is a further object of this invention to wire the piezocomposite transducer elements for sensing or for transmitting or for a combination of sensing and transmitting.
These and other objects are accomplished by an acoustic transducer comprising a honeycomb structure having a plurality of cells, each of the cells comprises a piezoelectric transducer, and each piezoelectric transducer comprises a stack having at least one piezocomposite element. Each of the plurality of cells comprises a multi-sided cell or a cylindrical cell depending on the configuration of the honeycomb structure.
The objects are further accomplished by an acoustic transducer array comprising a honeycomb structure having a plurality of cells, each of the cells comprises a piezoelectric transducer, each piezoelectric transducer comprises a stack having at least one piezocomposite element, each piezocomposite element includes a plurality of piezoceramic elements, the piezoceramic elements being arranged parallel to each other, the plurality of piezoceramic elements of the piezocomposite element being encapsulated in a polymeric matrix forming the piezocomposite element, a front planar surface and a back planar surface of the piezocomposite element comprise an electrically conductive layer, and a soft pressure release material is disposed around each stack except on a surface of the stack facing a front surface of the acoustic transducer array. The transducer array comprises means disposed adjacent to the plurality of cells for providing waterproofing of the acoustic transducer array. The honeycomb structure comprises a plurality of multi-sided cells. The honeycomb structure may also comprise a plurality of cylindrical cells. The honeycomb structure comprises a matrix of a plurality of strips attached together at cross-over points, the strips being made of an impact-resistant material. The honeycomb structure comprises a molded or drilled-out structure made of an impact-resistant material. The piezocomposite element comprises a 1-3 connectivity configuration. The piezocomposite element comprises a 2-2 connectivity configuration. Each piezocomposite element is separately wired for sensing as a single element. The piezocomposite element may be wired for sensing in a phased array configuration. Each piezocomposite element may be separately wired for transmitting as a single element. Each piezocomposite element may be separately wired for transmitting in a phased array configuration.
The stack comprises the piezocomposite element, an acoustic matching layer adjacent to a front surface of the piezocomposite element, and a stiffening layer adjacent to a back surface of the piezocomposite element. The stack may also include the piezocomposite element and a stiffening layer adjacent to a back surface of the piezocomposite element. The stack may further include the piezocomposite element and an acoustic matching layer adjacent to a front surface of the piezocomposite element. Each stack comprises wires extending from the front planar surface electrically conductive layer and from the back planar surface electrically conductive layer of the piezocomposite element for wiring the cells in a predetermined manner for operation of the acoustic transducer as a sensor array. Each stack comprises wires extending from the front planar surface electrically conductive layer and from the back planar surface electrically conductive layer of the piezocomposite element for wiring the cells in a predetermined manner for operation of the acoustic transducer as a transmitter array. Also, the stack may comprise a first piezocomposite element disposed adjacent to a second piezocomposite element, an acoustic matching layer adjacent to a front surface of the first piezocomposite element, and a stiffening layer adjacent to a back surface of the second piezocomposite element. In addition, the stack comprises a piezocomposite element, a first acoustic matching layer positioned adjacent to a front surface of the piezocomposite element, a second acoustic matching layer positioned adjacent to the first acoustic matching layer, and a stiffening layer adjacent to a back surface of the piezocomposite element.
The objects are further accomplished by the method of providing an acoustic transducer for operation in a rugged environment comprising the step of providing an impact-resistant honeycomb structure having a plurality of cells, each of the cells comprising a piezoelectric transducer.
The objects are further accomplished by the method of providing an acoustic transducer for operation in a rugged environment comprising the steps of providing an impact-resistant honeycomb structure having a plurality of cells, each of the cells comprises a piezoelectric transducer, and providing a stack in each piezoelectric transducer having at least one piezocomposite element.
The objects are further accomplished by a method of providing an acoustic transducer array for operation in a rugged environment comprising the steps of providing a honeycomb structure having a plurality of cells, each of the cells comprises a piezoelectric element, providing in each piezoelectric transducer a stack having at least one piezocomposite element, including a plurality of piezoceramic elements in each piezocomposite element, the piezoceramic elements being arranged parallel to each other, forming the piezocomposite element by encapsulating the plurality of piezoceramic elements of the piezocomposite element in a polymeric matrix, providing an electrically conductive layer on a front planar surface and a back planar surface of the piezocomposite element, and disposing a soft pressure release material around each stack except on a surface of the stack facing a front surface of the acoustic transducer array. The method comprises the step of providing means disposed adjacent to the plurality of cells for waterproofing the acoustic transducer array. The step of providing a honeycomb structure comprises the step of including in the honeycomb structure a plurality of multi-sided cells. The step of providing a honeycomb structure comprises the step of including in the honeycomb structure a plurality of cylindrical cells. The step of providing the honeycomb structure comprises the step of providing a matrix of a plurality of strips attached together at cross-over points, the strips being made of an impact-resistant material. The step of providing a honeycomb structure having a plurality of cells comprises the step of providing at least one piezocomposite element having a 1-3 connectivity configuration in each of the cells. The step of providing a honeycomb structure having a plurality of cells comprises the step of providing at least one piezocomposite element having a 2-2 connectivity configuration in each of the cells.
Additional objects, features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.